Insulating bushing



Feb 12 1924. 1,483,218

7 A. P. FAHNESTOCK INSULATING BUSHING Filed Sept. 2'7 1919 Patented Feb. 12, 1924.

UNITED STATES PATENT OFFICE.

ARCHIE P. FAHNESTOCK, OF LONG ISLAND CITY, NEW YORK, ASSIGNOB TO FAHNE- STOCK ELECTRIC COMPANY, A CORPORATION 01 WEST VIRGINIA.

INSULATING BUSHING.

Application filed September 27, 1919. Serial No. 326,815.

To a]! whom it may concern:

lie it known that I, Ancnm I. FAuNE- smock. a citizen of the United States, and a resident of Long Island City, county of Queens, and Stateof New York, have invented an Improvement in Insulating Bushings, of which the following is a specification.

This invention relates to appliances used in connection with the wiring of electrical circuits and more particularly to insulating bushings used in connection therewith.

An object of this invention is to provide a simple and effective insulating bushing that will be at once durable and practical in construction and use. A further object is to provide an insulating bushing that may be readily and easily applied and to provide aneflicient and positive device for retaining'such a bushing in position when once inserted into place. This invention has for another of its objects to provide a bushing that will greatly minimize the manual attention and care required to apply it to fixtures and the like and to insure greater reliability of action. Other objects will be ,in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter described and the scope of the application of which will be indicated in the appended claims.

Figure 1 and Figur 2 are side elevations showing the action of the device in its stages of application and use respectively,

Figure 3 is a cross-section showing details of construction,

Figure 4 is an end view, Figure 5 is a perspective view, and Figure 6 is a develop ment of certain features of the invention,

more particularly of the retaining or fastening device employed with the bushing proper.-

Similar reference characters refer to similar parts throughout the several views of the drawings.

Referring now to the drawings and particularly to Figure 3, there is shown a bushing 7 of a general cylindrical form composed of an insulating material such as porcelain, hard rubber or other composition and adapted for use in connection in general with wiring fixtures and appliances such as junction boxes, conduit boxes and the like for conducting electrical conductors 8 shown illustratively in Figure 3 through .a wall 9 which may be metallic'and which forms a part of the conduit. box or wiring fixture. The conductors 8 are carried through the opening 14 extending through the bushing proper. The wall 9 is provided with an aperture 10 into which the bushing 7 and its cooperating parts are inserted to carry the conductor through without abrasion or without danger of grounding the electrical circuit to the wall 9 itself. The wall 9 may be any wall through which it is desired to carry an electrical circuit.

Referring now more particularly to the construction of the bushing and associated parts, the bushing 7 is provided with shoulders 11 and 12 at its respective ends, there by forming a depressed or annular section 13 between the shoulders 11 and 12. The shoulder 11 is preferably made of greater diameter than the shoulder 12 for the purposes to be hereinafter described.

Mounted in the annular depression 13 between the shoulders 11 and 12 and substantially encompassing the body of the bushing is the spring locking 0r retaining device comprising a substantially circular collar member 15 having fingers 16 preferably integral therewith and extending in a direction generally coincident with that of the axis ofthe bushing itself. Figure 6 shows a development of this device which is madeof a spring metalv preferably of the nature of brass, phosphor bronze or'other material having resilient characteristics.- The collar member 15 thereof is preferably so formed into a split ring that relative motion between its ends may take place so that by virtue of its resiliency, it tends to expand in an outward or radial direction. The fingers 16 associated with the collar member 15 have the general conformity as shown in perspective in Figure 5 and more clearly in section in Figure 3, and have a tendency to spring outward by reason of the resiliency within themselves, assisted also by the outwardly expanding tendency of the split collar member 15. The spring fingers 16, by reason of the curvature given them at their extremities, have alsoa tendency to react in a direction substantially coincident with the direction of the axis since the resilient qualities of the material will cause them to resist against any tendency to com )ress them longitudinally of themselves. Figure 4 shows an end view of the resilient locking device. While in the drawings are shown four spring fingers cooperating with the collar member 15, it is obvious that a number other than four may be employed without departing, from the spirit of this invention.

The spring retaining device when placed in position in the annular recess 13 will have normally a diameter at its collar portion 15 corresponding substantially to the diameter of the shoulder 12 of the bushing proper, this diameter being preferably the limit to which the outwardly expanding collar 15 tends to spring. The length of the spring fingers 16 is preferably such that when the locking device is attached to the bushing 7 there will be a slight freedom of motion of the device between the shoulders 11 and 12. for a purpose to be hereinafter more particularly described. The wall 9 through which it is desired to lead an electrical conductor is provided with an aperture 10 whose diameter is sutficient to permit the free entry of the shoulder 12 of the bushing- The shoulder 11. however. is made of such diameter that it may abut on the side of the wall 9 forming the end face 17 of the aperture 10.

The operation of this invention is substantially as follows: After having provided the wall 9 with an aperture 10 of sutiicient diameter to permit the free entrance of the shoulder 12, the bushing 7 pro vided with the locking device is now inserted into the aperture 10. Figure 1 shows the action of the locking device during such insertion and shows the collar member 15 contracted due to the reaction of the spring fingers 16 against the interior walls of the aperture 10 and also shows the spring fingers 16 partially straightened or flattened in their curved end portions to permit the passage of the locking device through the aperture.

The freedom of motion or play of the retaining device in the annular depression 13 of the bushing permits the flattening out of the spring fingers 16 by allowing sufficient space for the increased length of the fingers due to such action thereof. The bushing is inserted to such a depth that the shoulder 11 reaches and abuts on the end face 17 of the aperture 10 thereby limiting the depth of the insertion.

Upon having reached the proper depth of insertion within the aperture, the resilient locking device react-s against the various parts of the structure and the wall to securely retain the bushing in place substantially as follows: The collar member 15 expands outwardly by reason of its resilient characteristics and carries the spring fingers 16 in an outward or radial direction. The spring fingers having also an inherent resiliency of their own with respect to the collar member 15 tend likewise to spring in an outward or radial direction and by reason of their curved end sections react against the walls of the aperture 10 to force the collar member 15 in contact with shoulder 12. The body of the bushing proper is thus placed in tension to hold the shoulder 11 firmly and positively in abutting contact with the end face 17 of the aperture. The curved sections of the spring fingers because of their curvature and their inherent resiliency due to such curvature. assist this action in reacting in a direction that is substantially coincident with the di rection of the axis of the bushing itself. thus positively and automatically locking and centering the bushing in position. The bushing and its locking device after such insertion is shown in side elevation in Figure 2 and in cross-section in Figure 3, from which a clearer understanding of the action of the device may be obtained.

In order to withdraw the bushing from the aperture in the wall, it is merely necessary to exert a force in the direction from shoulder 12 towards'shoulder 11, contracting the resilient. collar member and spring fingers 16 to the general form shown in Figure 1, whence the withdrawal of the bushing and its cooperating parts is readily accomplished.

It will be noted that there is provided in this invention a practical retaining device for bushings and like structures though it is to be understood that this invention is the not limited to insulating bushings alone and may be applied to allied and other structures. It will further be noted that this invention provides a bushing with a locking device which is extremely simple and inexpensive to manufacture and which may beapplied with the greatest facility and without the requirement of any particular manual skill. These objects and advantages as Well as others are attained without detracting from the effectiveness of operation and from the durability of the construction.

As various possible embodiments might be made of the above invention and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limlting sense.

I claim:

1. In a device of the class described, a bushin com osed of insulating material and adapted to l fe inserted into an aperture. a shoulder for limiting the depth of insertion of said bushing within said aperture and adapted to abut on the end face thereof, a second shoulder on said bushing, and resilient locking means cooperating with said second shoulder for maintaining said first shoulder in abutting contact with the end face of said aperture.

2. In a device of the class described, a bushing composed of insulating material and adapted to be inserted into an a erture, a shoulder for limiting the depth 0 insertion of said bushing within said aperture and adapted to abut on the end face thereof, a second shoulder on said bushing, and resilient locking means cooperating with said second shoulder for maintaining said first shoulder in abutting contact with the end face of said aperture and adapted to substantially center said bushing within said aperture.

3. In a device of the class described, an insulating bushing adapted for insertion into an aperture, a shoulder for abutting on the end face thereof, a second shoulder on said bushing, resilient means adapted to act in an axial direction against said shoulder for retaining said first mentioned shoulder in abutment with said end face and adapted to act also in a radial direction to substantially center said bushing within said aperture.

4. In a device of the class described, an insulating bushing adapted for insertion into an aperture, a shoulder for abutting on the end face of said aperture, and means including a plurality of spring fingers extending in an axial direction for resiliently retaining said shoulder in abutting contact with said end face.

5. In a device of the class described, an insulating bushing adapted for insertion into an aperture, a shoulder for abutting on the end face of said aperture, and means including a plurality of spring fingers adapted to react in an axial direction to retain said shoulder in abutting contact with said end face and adapted also to react in a radial direction to substantially center said bushing in said aperture.

6. In a device of the class described, an insulating bushing adapted for insertion into an aperture, a shoulder for abutting on the end face of said aperture, means including a plurality of spring fingers extending in an axial direction for resiliently retaining said shoulder in abutting contact with said end face and a second shoulder on said bushing for assisting said means.

7 In a device of the class described, a bushing composed of an insulating material and adapted to be inserted into an aperture and securing means for said bushing comrising an outwardly expanding spring colar provided with axially extending fingers.

8. In a device of the class described, an insulating bushing adapted for insertion into an aperture, means for retaining said bushing within said aperture, said means comprising an outwardly expanding spring member for reacting radially and a plurality of spring fingers extending axially for reacting in an axial direction.

9. In a device of the class described, an insulating bushing adapted for insertion into an aperture, means for locking said bushing within said aperture, said means comprising an outwardly expanding s ring member for reactingradially and a p urality'of spring fingers extending axially for reacting in both an axial and a radial direction,

10. In a device of the class described, an insulating bushing provided with a shoulder and retaining means for said bushing mounted thereon, said means being adapted to be sprung and moved in an axial direction into position over said shoulder.

11. In a device of the class described, an insulating bushing provided with a shoulder and a split collar retaining member mounted thereon, said member being adapted to be sprung into position over said shoulder.

12. In a device of the class described, an insulating bushing provided with a shoulder, a split collar having a normal diameter less than that of the shoulder and adapted to be sprung into place over said shoulder, and retaining means mounted upon said split collar.

13. In a device of the class described, an insulating bushing provided with a pair of shoulders to form a reduced section therebetween, a split collar member having a diameter normally less than that of the smaller of said shoulders and adapted to be sprung into said reduced section over said smaller shoulder, and retaining means mounted upon said split collar.

In testimony whereof, I have signed my name to this specification this 25th day of September, 1919.

ARCHIE P. FAHNESTOCK. 

